1. Field
One or more embodiments of the present invention relate to a photoacoustic probe used for a photoacoustic image diagnosis, and a photoacoustic diagnostic apparatus.
2. Description of the Related Art
Photoacoustic imaging technology is a technology for imaging biological tissues in a noninvasive way by using photoacoustic effects. If a short electromagnetic pulse of laser is incident on biological tissues, a portion of the energy is absorbed in the tissues and converted into heat, thereby generating a transient thermo-elastic expansion. As a result, ultrasound waves having frequencies of a wide range are released, and the ultrasound waves may be detected in various directions by a transducer for ultrasound waves to be converted into an image.
Since photoacoustic imaging is based on the conversion of optical energy into ultrasound waves for detection, this method has advantages of combining properties of optical imaging with those of ultrasound imaging. A pure optical imaging technology has a much higher contrast ratio than the ultrasound imaging technology. However, the pure optical imaging technology may form an image of biological tissues by only a predetermined depth from a surface of the biological tissues because of a high optical scattering in soft tissues. Compared to this, the ultrasound imaging technology has a high spatial resolution that enables a fetus inspection. The photoacoustic imaging technology is able to achieve both a high optical contrast and a high spatial resolution by overcoming a shallow imaging depth, which is the shortfall of the optical imaging, by an ultrasound conversion by photoacoustic effects.
There has been a significant progress in research for the photoacoustic imaging technology with respect to cancer, brains, hearts, and eyeballs of small animals. A photoacoustic imaging system may be easily fused with a conventional ultrasound imaging system, by only making a small revision (for example, a removal of an ultrasound transmission). Such an integrated system shares an acoustic detector, and thus, advantages of a traditional ultrasound imaging system such as portability and real-time imaging may be obtained in the integrated system.
However, for such a photoacoustic diagnostic apparatus, a laser of a short electromagnetic pulse is used, and, such a laser has a significant energy strength in general.